check_balanceCheck what an API key has spent and whether it has a spending limit. Use it to monitor key-level usage; limit-free keys draw on the account balance.
Show what this API key has spent and its own spending limit, if it has one. Free. Keys without a limit draw on the account balance, which API keys cannot read; the user sees it at https://apiko.app/dashboard/billing.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, non-destructive behavior, so the bar is lower. The description still adds real value beyond them: it states the call is free and discloses a hard limitation (API keys cannot read the account balance) that no annotation covers.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three short sentences, front-loaded with what is returned, then cost, then the limitation and fallback. The dashboard URL earns its place by telling the agent what to tell a user who needs the account balance.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
There is no output schema, so the description must carry the return-value burden, and it names the two returned concepts (spent amount and limit). It is slightly vague on what happens in the no-limit case (null vs. absent) but is otherwise complete for a zero-argument read.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool takes zero parameters, so the baseline is 4. Nothing in the description misrepresents the input surface, and the absence of arguments is consistent with a simple key-scoped lookup.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource: shows what the API key has spent and its own spending limit. It also scopes the answer precisely by ruling out the account balance, which is the main ambiguity for a balance-checking tool. Sibling names are unrelated resources, so sibling differentiation is not a meaningful test here.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Provides clear context for when the result is sufficient versus insufficient: keys without a limit draw on the account balance, which this tool cannot read, with a URL where the user can see it. That is a genuine conditional routing instruction, though it stops short of explicit 'use this when' phrasing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.